The factor fnow, in the Drake equation depends on
A) whether a civilization ever develops intelligence
B) whether a planet has any kind of life on its surface right now
C) how technologically advanced civilizations become
D) how long civilizations survive once they have arisen
D
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Electricity from a AAA battery costs the consumer about
A. 1 ¢ per kilowatt-hour B. 10¢ per kilowatt-hour C. $1 per kilowatt-hour D. $1000 per kilowatt-hour
A reasonable estimate for the duration of a typical physics lecture is
A) 600 s. B) 1000 s. C) 3500 s. D) 10,000 s.
The ______________ surrounds the nucleus of a comet
a. head or coma b. cloud c. fuzz d. cover e. epinucleus
Two metal rods, one silver and the other gold, are attached to each other end-to-end. The free end of the silver rod is immersed in a steam chamber at 100°C,
and the free end of the gold rod in an ice water bath at 0°C. The rods are both 5.0 cm long and have a square cross-section that is 2.0 cm on a side. No heat is exchanged between the rods and their surroundings, except at the ends. How much total heat flows through the two rods each minute? The thermal conductivity of silver is 417 W/m ? K, and that of gold is 291 W/m ? K. A) 8.2 kJ B) 9.5 kJ C) 12 kJ D) 14 kJ E) 16 kJ